The invention relates to an alcohol engine for a Flexible Fuel Vehicle (FFV) capable of using a gasoline fuel, an alcohol fuel or a mixed fuel of gasoline and alcohol, and more particularly to an apparatus for controlling the operation conditions of auxiliary equipments mounted on the engine, such as a supercharger and fuel pumps in response to concentration of the alcohol.
With an alcohol engine of this type, the alcohol concentration in a fuel varies from 0% to 100% depending upon the type of the supplied fuel. It is therefore necessary to control the engine in consideration of the alcohol concentration.
Japanese Patent Laid-open Publications Nos. 56-66424 and 61-218741 disclose that ignition timing and fuel injection amount are controlled in accordance with a detected alcohol concentration.
Generally, a supercharger is used for increasing air supply amount to the engine so that the output is increased correspondingly. However, under constant supercharging, the potential of an engine cannot be used sufficiently, depending upon the alcohol concentration.
In the meantime, fuel supply amount is required to be changed largely, e.g., about several times, if the alcohol concentration changes largely. In a conventional fuel supply system, an oil pump with a large capacity is necessary for supplying sufficient fuel. However, if the fuel injection amount becomes small at low alcohol concentration, returned fuel is increased. Therefore, energy generated by the engine is wasted and so much noises generate.